Conductivity measuring device for dry cleaning apparatus



Ndm l, 1959 MQBLMATHIEWS ErAL CONDUCTIVITY MEASURING DEVICE FOR DRYCLEANING APPARATUS Original Filed June 29. 1953 /j 29 a0 27 a 5' D I 3/Y m 8 86 J5 v 1 I v i 3 8557 War-- n 16 1 I 15 93 33 J? I Z4 a 36 J0 a5a0 93 X I Ill 5? -11 1 2' 3 Sheets-Sheet 1 Jeaader' Q M. B. M ATHEWSETAL 2,913,893 CONDUCTIVITY MEASURING DEVICE FOR DRY CLEANING APPARATUSNov. 24;"1'959' 3 Sheets- Sheet 2 Original Filed June 29. 1953 I mmvroksMr 0 My Nov. 24, 1959 M. B. MATHEWS EI'VAL v 2,913,893 CONDUCTIVITYMEASURING DEVICE FOR DRYCLEANING APPARATUS Original Filed Jun as. 1953.

' s Sheets-Sheet s wd m PM 0 CONDUCTIVITY MEASURING DEVICE FOR DRYCLEANING APPARATUS Martin B. Mathews, Chicago, and Leander O. Thnnberg,Riverdale, Ill., assignors to R. R. Street 8: Co., Inc., Chicago, 11].,a corporation of Illinois Original application 'June 29, 1953, SerialNo. 364,844. Divided and this application December 15, 1958, Serial No.780,330

26 Claims. (CI. 68--18) Our invention relates to the art ofdry cleaningof fabrics. It is particularly concerned with equipment to insuremaintenance of high cleaning efficiency of the dry cleaning solvent in asimple and effective manner. 7

In the usual process ofdry cleaning fabrics, the soiled fabrics aresubjected to the action of a volatile organic solvent which isimmiscible with water as, for example,

naphtha, Stoddard solvent, carbon tetrachloride, gasoline, benzene,trichloroethylene, and the like. Such solvents are effective for theremoval of grease or oil stains as Well as dust, dirt, lint and the likeWhich commonly adhere to the grease and oil It is conventional practice,in order to effect the removal of water-soluble stains, such as thosecaused by various foods and the like, to introduce into the volatileorganic solvent in the washer a small proportion of water, usually ofthe order of 0.05%. This is commonly done by utilizing, in conjunctionwith the dry cleaning organic solvent, a small proportion of anoil-soluble dispersing agent which may, for example, be an oil-solublehigher fatty acid soap or other type of anionic, cationic or nonionicdispersing agent but is very commonly an oil-soluble synthetic organicdetergent as, for example, long chain petroleum sulfonates such as themahogany sulfonates; sulfate'd fatty alcohols, such as lauryl sulfate;long chain sulfoacetates, such as 'lauryl sulfoacetate; long chain alkylsulfosuccinates such as dioctylsodiumsulfosuccinate; higher fatty acidmonoglycerides such as mono-olein; higher fatty acid monoglyceridesulfates, such as m'ono-olein mono-sulfates; and the like, the sulfatesand sulfonates being used in the form of salts. In the presence of suchdispersing agents, the Water added to the dry cleaning volatile organicsolvent is very finely orcolloidally dispersed throughout the solvent soas to form what is apparently, to the naked eye, a homogeneous solutionor what may be characterized as a pseudo solution. While the advantagesof the addition of water to a water-immiscible dry cleaning organicsolvent and the solubilizing of the water by means of an oil-solubledispersing agent have been, broadly speaking, heretofore known and used,the full potentialities of such existing knowledge have not beenutilized in practice because of the failure founderstand certain aspectsof the criteria which govern the conditions under which the dry cleaningoperation is best practiced. Thus, for instance, as almost invariablypracticed today, the amount of water added to the water-immiscible drycleaning solvent is based upon the weight and nature or condition of thefabrics added to the washer, a situation which is affected, among otherthings, by the relative'humid-ity in the atmosphere and by otherfactors. The real key to the matter of insuring uniform superior drycleaning inmodern reclamation systems lies in the discovery of therelationship and significance of electrical conductivity and the controland maintenance of the conditions which account for certainminimumelectricalconductivity essential for the-securing of theaforesaid results.

1n the dry cleaning operation proper, utilizing "such substantiallyclear homogeneous solutions," when the 2,913,893 h Patented Nov. 24,1959 "ice soiled fabrics are contactedwith the dry cleaning solution" inthe so-called washer for wheel, the fabrics absorb a certain amount ofsuch Water from the dry cleaning solution, the amount of such absorbedwater depending upon the nature and condition of the fabrics. Theremaining moisture in the dry cleaning organic solvent solution remainsmore or less constant during the cleaning operation of that particularbatch of clothes. How; ever, when a new batch of clothes or fabrics isintroduced into the washer and is contacted with such dry cleaningorganic solvent solution, an additional amount of the water dispersedtherein is abstracted or absorbedby the clothes or fabrics. The resultis that in the dry cleaning operations conducted by any plant themoisture content of the volatile organic solvent solution varies quiteconsiderably from batch to batch of soiled fabrics and, at variousstages of the use thereof for the cleaning of different batches ofclothes or fabrics, the moisture content drops to a point where it isinadequate to serve its intended purposes, and the cleaning results arenonuniform.

In the dry cleaning step proper, as carried out in the so-called washeror wheel, it has been the practice to utilize various concentrations ofoil-soluble soaps or de tergents as, for example, from a small fractionof one percent to as high as seven percent or even higher. During thecleaning of various batches of clothes, the concentration of the soap ordetergent decreases and it has, therefore, been the practice toreplenish the soap or detergent from time to time. 7

Despite all of such prior knowledge and practices, serious difiicultiesand lack of significant knowledge have existed so that, from a practicalstandpoint, it has not been possible for the operator of a dry cleaningestablishment to carryout the dry cleaning operations in such a manneras to obtain uniform, substantially optimum results from batch to batchof fabrics being cleaned.

It has been discovered that outstandingly satisfactory uniform cleaningresults of high efiiciency can be obtained in a simple, safe andpractical manner by procedure which may readily be understood andpracticed by the average operator of a dry cleaning establishment. Thisinvention is based, in part, on the discovery that, in dry cleaning withwater-immiscible organic solvent solutions containing an oil-solubledispersing agent or dry cleaning soap or detergent and water, as moreparticularly described below, the electrical conductivity of suchsolutions should be maintained at not less than about l0 l0 mhos toinsure uniformly superior overall re sults with respect to removal ofinert soil, water-soluble soil, prevention of soil redeposition,whiteness retention, avoidance of deleterious action On fabrics, economyof detergency consumption, and freedom from interference with properoperation of the filtration and distillation systems. The amount andtype of dry cleaning dispersing agent or detergent and the amount ofwater influence the degree of electrical conductivity imparted to thedry cleaning water-immiscible organic solvent. However, the state ofdistribution of the water is also a very important factor. In all cases,for the effective practice of this invention, the water must be sofinely or colloidally dispersed in the organic solvent as to produce asubstantially clear homogeneous fsolutionj so far as the naked eye isconcerned, or What may be characterized as a pseudo solution. tln thisconnection, it may be noted that it is entirelypossible to providemixtures of water-immiscible organic solvents and oil-soluble dispersingagents and water, identical in proportions such as have been found to beespecially effective as hereafter described, and still be unsatisfactoryfor purposes of this invention because their electrical conductivityfalls appreciably below the aforesaid value of 10x10 mhos due to thefact that the water is not properly distributed through the organicsolvent. Hence, it will be understood that when we speak herein ofsolutions containing oil-soluble dispersing agents or detergents andwater, it will be understood that we meansuch solutions. wherein thewater is so finely dispersed as to form a substantially clearhomogeneous solution in the water-immiscible organic solvent, as viewedby the naked eye. It is also important, for the most effective practiceof this invention, that the entire system be charged with water so thatthe solubilized water passes through the filter. I

This invention is based upon the utilization of equipment which, inpractice, involves periodically determining the electrical conductivityof the aforesaid dry cleaning solutions and, if, during use of suchsolutions in the cleaning of a batch or successive batches of soiledfabrics, the electrical conductivity has dropped toappreciably below l10- mhos, an amount of water is added to the solution so as to bring theelectrical conductivity thereof to not less than the aforesaid minimumvalue thereof, this being coupled, if necessary, with the replenishingof the soil-soluble dispersing agent or dry cleaning detergent.

This invention is particularly advantageously practiced with theutilization, as the oil-soluble dispersing agent, of sulfate andsulfonate detergents containing an alkyl group of at least 8 carbonatoms and usually between 8 and 18 carbon atoms, in the form of saltsthereof as, for instance, the alkali metal, ammonium and amine salts. Inaddition to the examples thereof described above, salts of higher alkylaryl sulfonates such as dodecyl benzene -sulfonate, octyl benzenesulfonate, nonyl naphthalene sulfonate, keryl benzene sulfonates, andthe like can be utilized. It is also particularly advantageous, in theespecially preferred embodiments of this invention, to utilizeproportions of oil-soluble dispersing agent or detergent, on thenon-volatile basis, of not less than about 1.5%, based on the volume ofthe organic solvent, and desirably within the range of about 1.5% toabout 3%, a good average being about 2%. In this connection, it will beunderstood that dry cleaning detergents are commonly marketed in theform of liquid or paste products and frequently contain diluents,volatile ingredients and the like over and above the nonvolatile drycleaning detergents proper. When we speak of, for example, 1.5% to 3% ofthe dry cleaning detergent, said percentages are on the non-volatileactive detergent basis. I

The amount of water added to the water-immiscible dry cleaning solventshould, in the particularly preferred embodiments of this invention, notbe appreciably less than 0.2%, by volume, and most desirably ranges fromabout 0.2% to about 0.4%, it being relatively uncommon that this latterfigure will be exceeded. So far as actual cleaning practice goes, theseamounts of water are abnormally large but their use, under theconditions of the present invention, has been found to be mostadvantageous, cleaning of the fabrics being enhanced and subsequentspotting operations being reduced to a substantial minimum.

The optimum conditions under which the dry cleaning operation should beconducted, taking into account the over-all aspects, therefore, will, ingeneral, involve the utilization of a water-immiscible dry cleaningorganic solvent solution containing from about 1.5% to about 3%, with agood average of about 2%, of an oil-soluble sulfate or sulfonatedetergent containing an alkyl group of at least 8 carbon atoms, and fromabout 0.2% to about 0.4%, with a good average of about 0.3%, of water,the electrical conductivity of said solution being not less than about10 10' mhos.

In the light of the foregoing description, it will bev understood that,in the case of the foregoing dry cleaning organic solvent solutions, theelectrical conductivity varies more or less uniformly as a function ofthe water and detergent content of such solutions, the greater the waterand detergent content, at least within practical op- 4 erating ranges,-the greater the electrical conductivity. Within any given systemutilizing a particular waterimmiscible dry cleaning organic solvent, aparticular detergent and water, a substantially fixed relationshipexists with respect to the variability of the electrical conductivity asa function of the qauntity of detergent and water, particularly thelatter, dissolved or colloidally dispersed in the organic solvent in theform of the aforesaid solutions. Thus, with any given system, forexample, one utilizing Stoddard solvent as the dry cleaning organicsolvent, di-(Z-ethylhexyl) sodiumsulfosuccinate as the dispersing agentor detergent, and distilled water as the source of water, it is possibleto plot curves showing the relationship of electrical conductivity todetergent and water content, particularly-the latter, within practicallimits of the latter. Other curves can readily be prepared based uponelectrical conductivity data utilizing any specific system of materials.

It will be understood that, through continued use of the dry cleaningsolution on difierent'batches of soiled fabrics, said solution builds upa constantly varying amount of soluble impurities which afiect to agreater or lesser extent, depending upon the amount and nature of suchimpurities, the electrical conductivity. of said solution. In the usualcase, this is not sufficient substantially to affect adversely theconductivity readings so far as their reflecting the condition of thesolution with respect to the content of water and detergent therein. Inthe usual case, the electrical conductivity readings of a solutioncontaining a relatively high proportion of soluble impurities resultingfrom long continued use of the solution prior to distillation thereofwill show a somewhat lower conductivity than a similar pure organicsolvent solution containing the same amounts of only the oil-solubledetergent and water. Suitable extrapolations can be resorted to, ifdesired, in situations of this kind, if deemed advisable, to take intoaccount the effect of soluble impurities on the electrical conductivityof repeatedly used dry cleaning solutions. Extreme temperaturevariations in the solution also influence the electrical conductivityvalue of the solution, high temperature increasing and low temperaturesdecreasing the electrical conductivity. Suitable allowances may be madefor such temperature variations and optimum results are enjoyed bymaintaining the temperature of the solution between substantially 70 toF.

While satisfactory results are obtained with electrical conductivitiesmaintained at notless than about 10 l0-' mhos, we prefer to operate athigher levels as, for example, from about 40 to about 120x l0- mhos oreven higher, a particularly preferred range being from about 50 to aboutx 10- mhos.

In the preferred manner of carrying out the present invention, in theso-called two bath system, for example, in dry cleaning systems whichinclude a washer-filter-trap assembly reserved for the detergentsolution, and a separate rinse and filter system, and wherein saidsolution is continuously circulated through said washer-filter-trapassembly, the water-immiscible liquid organic solvent is activated withthe requisite amount of oil-soluble non-volatile'dry cleaning dispersingagent or detergent and the resulting solution is circulated through saidassembly to effect uniform distribution of said dispersing agent ordetergentthroughout the entire body'of organic solvent in the assembly.The requisite amount of Water is then added and the resulting mixture'is circulated through said assembly whereby to solubilize the waterthroughout the system, so that the solubilized water solution passesthrough the filter, and forms a substantially clear homogeneous solutionhaving an electrical conductivity not less than about 10x10? mhos. Thesoiled fabrics to be dry cleaned are then subjected to the resulting drycleaning solution in the usual way, successive batches of soiled fabricsbeing dry cleaned. The electrical conductivity of the solution" ismeasured and,

u) if the electrical conductivity has dropped to below the aforesaidvalue, an additional amount of water and, if necessary, detergent isadded to bring the concentration of the water and detergent and theelectrical conductivity of the solution to within the predeterminedranges. It will, of course, be understood that after the fabrics arecleaned they are rinsed and dried and fluffed in accordance withstandard practices in the art.

It will be understood that the addition of oil soluble dispersing agentor detergent to the organic solvent solutions will occur far moreinfrequently than the additions of water. In this connection, it will beappreciated that the solubility and stability of the oil-solubledispersing agent or detergent are such that the content thereofdiminishes quite slowly so that replenishing thereof is necessary atonly relatively sporadic intervals. Hence, when the electricalconductivity drops below about 1O 10' mhos it will, in most cases, benecessary to add only water in order to increase the electricalconductivity to a value above said minimum figure. The content ofoilsoluble detergent in the dry cleaning solution can be determined fromtime to time by heretofore known procedures. It may be found, in certaininstances, that when the electrical conductivity drops below theaforesaid minimum value there may be a deficiency of both detergent andwater, and, in such cases, both detergent'and water will be added tobring the amounts thereof within the desired or predetermined ranges aswell as restoring the electrical conductivity of the dry cleaningsolution to a value not below said minimum figure. In the usual case,however, as stated, water additions alone will be sufiicient and thedetergent content can be determined and maintained at desiredproportions by procedures already known in the art.

An object of this invention is to provide an improved system ofapparatus for measuring or determining the electrical conductivity ofthe solution circulating through the dry cleaning system for the purposeof maintaining high cleaning efficiency in a simple and effectivemanner. In this respect all of the circulating solution in the drycleaning system is circulated in a continuous manner through theconductivity measuring apparatus in order to obtain accurate andcontinuous measurements and determinations of the electricalconductivity thereof, and said conductivity measuring apparatus offerssubstantially no impedance or restriction to the circulation of thesolution. The apparatus is simple in construction and may beinexpensively manufactured and installed.

A further object of this invention is to provide an improved system ofapparatus for automatically supplying water to the solution in the drycleaning system for automatically maintaining the electricalconductivity of the solution at the desired values and to prevent aninadvertent and excessive supply of water thereto. The water isintroduced into the system for the purpose of maintaining a certainminimum electrical conductivity value necessary for efiicient cleaning,compatible with avoidance of damage to the fabrics, such as excessivewrinkling and shrinkage, which may be brought about by excess water.

In this respect suitable water pipes, water reservoir and solenoidvalves and signal lights controlled by the electrical conductivitymeasuring apparatus are utilized.

Further objects of this invention reside in the details of constructionof the measuring and control apparatus and in the cooperativerelationships between the com; ponent parts thereof.

Other objects and advantages of this invention will become apparent tothose skilled in the art upon reference to the accompanyingspecification, claims and drawings in which; i

Figure 1 is an elevational view of a dry cleaning system embodying thefeatures of this invention;

Figure 2 is a wiring diagram for the equipment illustrated in Figure 1;

estates Figure '3 is a vertical sectional view through the electricalconductivity responsive device and taken substantially along the line 33 of Figures 2 and 4;

Figure 4 is 'a horizontal sectional view taken substantially along theline 44 of Figure 3;

Figure 5, is a horizontal sectional view taken substantially along theline 55 of Figure 3;

Figure 6 is a sectional view of one of the spacer members illustrated inFigure 3;

Figure 7 is an enlarged partial sectional view showing the manner ofmaking electrical contact with the electrodes as illustartedin Figure 3;

Figure 8 is a vertical sectional view similar to Figure 3 butillustrating a further formof the invention and taken substantiallyalong the line 8-8 of Figure 9;

Figure 9 is a horizontal sectional view taken substantially along theline 9 9 of Figure 8;

Figure 10 is a horizontal sectional view taken substantially along theline 1010 of Figure 8;

Figure 11 is a sectional view through one of the spacer membersillustrated in Figure 8.

Referring first to Figure 1, there is generally illustrated aconventional dry cleaning system or apparatus such as known in the tradeas Prosperity 6A. It includes a dry cleaning washer 10 supported by feet11 and having an access door 12 through which apparel to be dry cleanedis inserted. It also includes a filter 13 supported by feet 14 andhaving a removable cover 15. The filter 13 is provided with an inletfitting 16 and an outlet fitting 17.

The dry cleaning solution is withdrawn from the washer 10 through aconduit 20, a button trap 21 and a conduit 22 bymeans of a pump 23driven by an electric motonnot' shown. The pump discharges through aconduit 24 into the filter 13 through the fitting 16. The conduit 24 maybe provided with a sight glass 25. The solution is discharged from thefilter 13 through the discharge fitting 17, an upwardly extendingconduit 26, a horizontally extending conduit 27 and a downwardlyextending conduit 28 into the washer 10. Thus, the pump 23 operates tocirculate the solution from the washer it) through the button trap 21,the filter 13 and back to the washer 10. A valve 29 and a sight glass 30may be located in the horizontal conduit 27. The conductivity device 31of this invention is preferably vertically arranged in the verticalconduit 26 adjacent the horizontal conduit 27 on the discharge side ofthe filter 13. In this connection the conductivity responsive device 31is connected by a reducing fitting 32 to the conduit 26 and by aT-fitting 33 to the conduit 27. One through leg of the T-fitting 33 issecured to the conductivity responsive device 31 and the other throughleg thereof is closed by a plug 34. The normal leg is connected to thehorizontal conduit 27 The details of construction of the electricalconductivity responsive device are illustrated in Figures 3 to 7. It isshownto be constructed for use with a two inch conduit system, that is,where the vertical conduit 26 is formed from standard two inch pipe.Here, the electrical conductivity responsive device 31 includes acylindrical housing 36 which may be formed from a three inch pipe or itmay be formed from a casting, if so desired. The cylindrical housing 36is threaded at its lower end as indicated at 37 and is secured to thereducing coupling 32 which in turn is secured to the conduit 26. Thehousing is also threaded at its upper end as indicated at 38 so that itmay be secured to the T-fitting 33 which in this. instance is a threeinch T-fitting wherein the through legs. of the T-fittingare three inchand the normal leg is of smaller size as, for example, a two inch legfor connection to the horizontal conduit 27 when it is a two inchconduit. Concentrically located within the housing, 36 are a pair ofconcentric tubular metallic electrodes 39 and 40. These electrodes 39and 40 may be made of any suitable metal which will not be affected bythe:

solution. For example, the inner electrode 39 may be formed of No. 16gauge seamless steel tubing having an outside diameter of 2% inch andthe outer electrode 40 may be formed of No. 16 gauge seamless steeltubing having an outside diameter of 2% inch. It will be noted here thatthe inside diameter of the inner tubular electrode 39 is substantiallythe same as the inside diameter of the two inch conduit 26 so that theelectrodes 39 and 40 will not restrict the flow of the solution throughthe dry cleaning system. The electrodes 39 and 40 are held in concentricrelation within the housing 36 by means of lower and upper spacermembers 41 and 42.

The lower and upper spacer members 41 and 42 are each provided with acentral opening 44 which corresponds to the inside diameter of the innerelectrode 39. The spacer members 41 and 42 are made of an electricalinsulating material such as Lucite. Adjacent the opening 44 in thespacer member there is provided an annular seat 45 which receives theend of the inner electrode 39. It is also provided with an annular seat46 of larger diameter for receiving the end of the outer electrode 40.Between the seats 45 and 46 the spacer member is provided with aplurality of openings 47 so that the solution in addition to flowingthrough the inner tubular electrode 39 is also allowed to flow betweenthe inner electrode 39 and the outer electrode 40. Substantially freeflow of the solution is provided between the electrodes 39 and 40because of the relatively large number of these openings 47. The innerelectrode 39 is secured to the lower spacer member 41 by means of ascrew 49 received in a counterbored hole 50 in the spacer member, thescrew 49 being screwed into a tapped hole in the lower end of the innerelectrode 39.

The lower spacer member 41 is secured in place in the housing 36 bymeans of a pair of screws 51 and 52 which are screwed into the spacermember 41. It is here noted that the screws 51 and 52 do not toucheither electrode 39 and 40 so that there can be no electrical conductionbetween the electrodes 39 and 40 and the housing 36 through these screws51 and 52. The screws 51 and -2 are sealed against leakage by washers orgaskets 53 which may be formed of Lucite. In this way the spacer member41 is secured to the housing 36 which in turn concentrically mounts thelower ends of the tubular electrodes 39 and 40. The upper spacer member42 is secured to the housing 36 by means of a pair of screws 54 and 58.The screw 54 is threaded into the upper end of the inner electrode 39 soas to make electrical contact therewith. The screw 54 is sealed againstleakage and is electrically insulated from the housing 36 by means of anelectrical insulator 55 which also may be made of Lucite. The screw 54has a tapped hole therein for receiving a screw 56 to form an electricalconnector for a conductor 57. The screw 58 is threaded into the upperend of the outer electrode 40 so as to make electrical contacttherewith. It is also sealed against leakage and electrically insulatedfrom the housing 36 by means of an insulator 55 and it is also providedwith a tapped hole for receiving a screw 56 for forming an electricalconnection to a conductor 59. Thus, the screws 54 and 58 in addition tosecuring the upper spacer member 42 and the upper ends of the electrodes39 and 40 in place, also act as electrical connectors for makingelectrical connection to the electrodes 39 and 40, respectively.

It is therefore seen that all of the solution being circulated throughthe dry cleaning system is circulated through the electricalconductivity responsive device 31, the solution passing through theinner electrode 39 and between the inner and outer electrodes 39 and 40.Thus, the electrodes 39 and 40 may operate continuously to measure ordetermine the electrical conductivity of the solution. At the same timethe electrical conductivity responsive device 31 offers substantially norestriction or resistance to the flow of the solution therethrough. Inthis way accurate determinations may be made.

In the Figures 8 to 11 the electrical conductivity responsive device 31is constructed for use with a three-inch conduit system, that is, wherethe vertical conduit 26 is formed from a pipe of three inch diameter.Here, the housing 36 is made larger as, for example, from a four inchpipe and likewise the T-fitting 33 is a four inch fitting. However, theelectrodes 39 and 40 may be of the same size as in Figures 3 to 7 sothat they may be interchangeably used. Here, the spacer members aredesignated at 62 and 63; They correspond in all respects to the spacermembers 41 and 42 with the exception that they are provided with aplurality 'of outwardly extending ears 64 to form openings between thespacer members and the housing 36, these openings being designated at65. The cars 64 may be integrally formed on the spacer members 62 and 63or they may be made from separate pieces such as Lucite which in turnare secured to the spacer members 62 and 63 by a suitable cement such asethylene dichloride. The solution flowing through the electricalconductivity responsive device 31 in Figure 8 in addition to flowingthrough the inner electrode 39 and between the inner electrode 39 andthe outer electrode 40 also flows between the outer electrode 40 and thehousing 36. In this way substantially no restriction or resistance tothe flow of the solution is provided by the electrical conductivityresponsive device and, yet, accurate measurements of the electricalconductivity of the solution may be obtained.

Referring now to Figures 1 and 2, the system of this invention includesan electrical resistance responsive device for measuring or determiningthe electrical conductivity of the solution" flowing through the drycleaning system. This electrical resistance responsive device maycomprise an adjustable Wheatstone bridge arrangement. It has a terminalstrip 71 and a selector switch 72 cooperating with indicia 73 fordetermining the adjustment of the bridge. The bridge may be powered byany suitable source of electrical energy transmitted thereto throughline wires 74 and 75 connected to terminals "76 and 77, respectively.One of the legs of the bridge circuit may be connected to terminals 73and 79 which in turn are connected by the conductors 57 and 59 to theelectrodes 39 and 40 in the electrical conductivity responsive device31. In this way the electrical conductivity of the solution, asdetermined by the resistance to current flow therethrough, is utilizedfor balancing and unbalancing the bridge in the electrical resistanceresponsive device 70, the balancing point of which may be adjusted toany desired value by manipulating the knob 72. The bridge circuit in theelectrical resistance responsive device 70 operates switching means forconnecting the line wires 74 and 75 across the terminals 80 and 81 andfor connecting those line wires across the terminals 86 and 82. When theelectrical conductivity of the solution is above a predetermined valueas determined by the setting of the control knob 72, the line wires 74and 75 are connected across the terminals 80 and 81 by the switchingmechanism. When the electrical conductivity of the solution is below thepredetermined value, the line wires 74 and 75 are connected across theterminals 80 and 82.

Water is supplied to the solution from a water reservoir which issuitably supported in an elevated position as by securing the same tothe conduit 28 as indicated in Figure 1. Water is supplied to thereservoir 85 by means of a water supply pipe 86. A solenoid valveconsisting of a valve 87 and a solenoid operator 88 is located in thepipe 86 for turning on and off the water. The pipe 86 also has a secondvalve 89 which is controlled by a float 90 responsive to the level ofthe water in the reservoir 85. When the solenoid 88 is energized to openthe valve 87, water flows into the reservoir 85 up to a predeterminedlevel therein whereupon the float 90 closes the valve 89 to shut off thesupply of water to the reservoir. Water is fed from the reservoir 85into the conduit 22 and, hence, into the circulating solution in the drycleaning system through a' pipe WhlChis" connected by a petcock 933 intothe conduit" 22: By

suitably'adjusting the petcock 92the rate ofwater feed into the watersolution may be regulated; The pipe 91 is preferably provided with astrainer 93- for keeping foreign matter out of the solution. The flow ofwater through the pipe 91may' be-turned on-and' off by a valve operatedby a solenoid 95L- When the solenoid 95 is energized, the valve 94 isopenedto supply water to the solut on and, when the'solenoi'd 95isdeenergized, the

valve 94 is closed. A signal light 96 having an indicating lamp 97isconnected in paralled with the solenoid 95 so that the signal light isilluminatedwhile waterisbeing supplied to the solution in the drycleaning system. To prevent opening of the valve 94 when the pump 23 isnot running there is provided a relay having an operating coil 98 foroperating a switch arm 99, the operating coil 98 being connected byconductors 100 and 101 to the controlling switch for operating the motorwhich drives the pump 23. V

In starting the dry cleaning system the water reservoir 85 is firstfilled with water and then the pump 23 isturned on for circulating thesolution through the washer and filter. The solution is checked for theamount of'oilsoluble non-volatile dry cleaning detergent to assure thata. proper amount of the detergent is present in the solution. Theautomatic control system is then activated; When the pump 23 is placedin operation, the switch 99 operated by the operating coil 98 is closed.If the electrical conductivity of the solution is below the desiredvalue as determined by the control knob 72, a circuit is completed fromthe line wire 74 through terminal 76, terminal 82, conductor 105',switch 99, signal light 96 and solenoid 95 connected in parallelconductor 103, terminal 80 and terminal 77 back to the line wire 75.This energizes the'solenoid 95 for opening the valve 94 to supply waterfrom the reservoir 85 to the conduit" 22 and, hence, to the solution inthe dry cleaning system. The rate of application of the Water to thesolution is regulated by the petcock 92. At the same time the indicatinglamp 97 is illuminated. When the electrical conductivity of thesolution'reach'es. the desired value, the aforementioned circuitisbroken and an-. other circuit is completed from the line wire 74through terminal 76, terminal 81, conductor104, solenoid 89, conductor103, terminal 80 and terminal 77 back to the line wire 75, this circuitbeing completed at the same time that the aforementioned circuit isbroken. As a result, the indicating lamp 97 is extinguished, thesolenoid 95 is deenergized to close the valve 94 to shut off the supplyof water to the solution and the solenoid 88 is energized to open thevalue 87 to supply water to the reservoir running from ten: to twentyminutes depending upon the type; of garments being: cleaned; If water isintroduced intermittently'during a cleaning cycle for shorter periods,this means that the water is being introduced at too great a rate and"to remedy this the petcock 92 is closed off somewhat in order to obtainthe correct cycling. If water is admitted to the solution for longerperiods than this two to five minute period, this indicates thatsomething is wrong and: theoperator is advised of this by the signallight 96. The amount of water introduced into the solution. may beregulated by adjusting the control knob 72 on. the electrical resistanceresponsive device 70, the knob being turned in one direction forincreasing the amount of water in solution" and in the other directionfor decreasing the amount of such water.

While-for. purposes of illustration one main form of this invention hasbeen disclosed, other forms thereof may become-apparent to those skilledin the art upon reference to this disclosure, and therefore, thisinvention is to be limited only by'the scope of the appended claims.

This application is a division of our application Serial No. 364,844,filed June 29, 1953.

We. claim as. our invention:

1; In a. dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting'the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile di'ycleaning detergent and water so finely dispersed as'to: form a;substantially clear homogeneous solution, the improvement whichcomprises a substantially cylindricalhousing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulatedfrom each other and thehousing, the space between said concentrically arranged tubular metallicelectrodes. being traversed by a portion of the circulating solution,and an electrical resistance responsive devicev electrically connectedto said metallic elec-.

trodes for'responding to the electrical conductivity of the solution;

2. In, a dry cleaning system which includes a washer solution, theimprovement which comprises a substanis being suppliedto the reservoir85 forfilling the same.

If for some reason the control apparatus should not operate properly wasto tend to supply water to the solution in excessive amounts, the amountof water so supplied is limited by the size of the reservoirl85. In thisway it is impossible to add excessively large amounts of water to thesolution. Also in this way the correct amount of water is maintained inthe solution for providing maximum dry cleaning efliciency.

When garments are placed in the washer 10, they will absorb some of thewater in the solution and, when this occurs, the control system of thisinvention automatically operates to replenish the water so absorbed soas to maintain at all times maximum cleaning efiiciency regardless ofthe character of the garments beingcleaned and the moisture contentcarried by such garments. The signal light 96 is illuminated during thetime that the tially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a sole-. noid valve for supplyingwater to the solution in the ductivity of the solution for maintainingthe water content of the solution at substantially a desired value.

3. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump 11 for circulating through the washer, filter andconduits a water-immiscible'organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afloat valve for supplying water to a predetermined level in the waterreservoir, a water delivery pipe for supplying water from the reservoirinto the solution in the system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to the electricalconductivity of the solution and controlling said solenoid valves tosupply water from the water reservoir to the solu-' tion and to shut offthe supply of water to the water reservoir when the electricalconductivity of the solution falls below a desired value, and to shutoff the supply of water from the water reservoir to the solution and tosupply water to the water reservoir when the electrical conductivity ofthe solution rises above the desired value, for maintaining the watercontent of the solution at substantially the desired value and forpreventing an excess supply of water to the solution.

4. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, con duits interconnecting theWasher and filter and'a pump for circulating through the washer, filterand conduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduitsvfor circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a solenoid valve for sup plyingwater to the solution in the system, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valve for controlling the supply of water to thesolution in accordance with the electrical conductivity of the solutionfor maintaining the water content of the solution at substantially adesired value, and a signal light electrically connected to saidcontroller and illuminated While water is being supplied to thesolution.

5. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afloat valve for supplying water to a predetermined level in the waterreservoir, a water delivery pipe for supplying water from the reservoirinto the solution in the system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to said solenoidvalves to supply water from the water reservoir to the solution and toshut oh the supply of water to the water reservoir when the electricalconductivity of the solution rises above the desired value, formaintaining the water content of the solution at substantially thedesired value and for preventing an excess supply of water to thesolution, and a signal light electrically connected to said controllerand illuminated while water is being supplied to the solution.

6. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a solenoid valve for supplyingwater to the solution in the system, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valve for controlling the supply of water to thesolution in accordance with the electrical conductivity of the solutionfor maintaining the water content of the solution at substantially adesired value, and switch means operatively connected to the pump andelectrically connected to the solenoid valve which controls the supplyof water to the solution for preventing the supply of water to thesolution when the pump is not operating.

7. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afioat valve for supplying water to a predetermined level in the waterreservoir, a water delivery pipe for supplying water from the reservoirinto the solution in the system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to the electricalconductivity of the solution and controlling said solenoid valves tosupply water from the water reservoir to the solution and to shut offthe supply of water to the water reservoir when the electricalconductivity of the solution falls below a desired value, and to shut ohthe supply of water from the water reservoir to the solution and tosupply water to the water reservoir when the electrical conductivity ofthe solution rises above the desired value, for maintaining the watercontent of the solution at substantially the desired value and forpreventing an excess supply of water to the solution, and switch meansoperatively connected to the pump and electrically connected to thesolenoid valve which controls the supply of water to the solutionforpreventing thesupply of waterto the solution when the pump is notoperating.

8. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting thewasher'and filter and a pump for circulating through the washer, vfilterand conduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a solenoid valve for supplyingwater to the solution in the system, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valve for controlling the supply of water to thesolution in accordance with the electrical conductivity of the solutionfor maintaining the water content of the solution at substantially adesired value, and a signal light electrically connected to saidcontroller and illuminated while water is being supplied to thesolution, and switch means operatively connected to the pump andelectrically connected to the solenoid valve which controls the supplyof water to the solution for preventing the supply of water to thesolution when the pump is not operating.

9. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, con- 1 duits interconnecting thewasher and filter and a pump for circulating through the washer, filterand conduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises a substantially cylindrical housing connected into one of theconduits for circulation of the solution therethrough, a pair of spacedapart concentrically arranged tubular metallic electrodes concentricallymounted in the housing and electrically insulated from each other andthe housing, the space between said concentrically arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afloat valve for supplying water to a predetermined level in the waterreservoir, awater delivery pipe for supplying water from the reservoirinto the solution in the system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to the electricalconductivity of the solution and controlling, said solenoid valves tosupply water from the water reservoir to the solution and to shut offthe supply of water to the water reservoir when the electricalconductivity of the solution falls below a desired value, and to shutoff the supply ofwater from the water reservoir to the solution and thesupply water to the water reservoir when the electrical conductivity ofthe solution rises above the desired value, for maintaining the watercontent of the solution at substantially the desired value and forpreventing an excess supply of water to the solution, and a signal lightelectrically connected to said controller and illuminated while water isbeing supplied to the solution, and switch means operatively connectedto the pump and electrically connected to the solenoid valve whichcontrols the supply of water to the solution for preventing the supplyof water to the solution when the pump is not operating.

10. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble non-volatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the system andhaving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a solenoid valve for supplyingwater to the solution in the system, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valve for controlling the supply of water to thesolution in accordance with the electrical conductivity of the solutionfor maintaining the water content of the solution a substantially adesired value.

11. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through. the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and Water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the system andhaving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afloat valve for supplying water to a predetermined level in the waterreservoir, a water delivery pipe forsupplying water from the reservoirinto the solution in the, system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and 'an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to the electricalconductivity of the solution and controlling said solenoid valves tosupply water from the water reservoir to the solution and to shut offthe supply of water to the water reservoir when the electricalconductivity of the solution falls below a desired value, and to shutoff the supply of water from the water reservoir to the solution and tosupply water to the water reservoir when the electrical conductivity ofthe solution rises above the desired value, for maintaining the watercontent of the solution at substantially the desired value and forpreventing an excess supply of water to the solution.

12. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand. filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble non volatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solu- 15 electrically connected to saidmetallic electrodes and said solenoid volve for controlling the supplyof water to the solution in accordance with the electrical conductivityof the solution for maintaining the water content of the solution atsubstantially a desired value, and a signal light electrically connectedto said controller and illuminated while water is being supplied to thesolution.

13. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the system andhaving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afloat valve for supplying water to a predetermined level in the waterreservoir, a water delivery pipe for supplying water from the reservoirinto the solution in the system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to the electricalconductivity of the solution and controlling said solenoid valves tosupply water from the water reservoir to the solution and to shut oilthe supply of water to the water reservoir when the electricalconductivity of the solution falls below a desired value, and to shutolf the supply of water from the water reservoir to the solution and tosupply water to the water reservoir when the electrical conductivity ofthe solution rises above the desired value, for maintaining the watercontent of the solution at substantially the desired value and forpreventing an excess supply of water to the solution, and a signal lightelectrically connected to said controller and illuminated while water isbeing supplied to the solution.

14. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the system andhaving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a solenoid valve for supplyingwater to the solution in the system, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valve for controlling the supply of water to thesolution in accordance with the electrical conductivity of the solutionfor maintaining the water content of the solution at substantially adesired value and switch means operatively connected to the pump andelectrically connected to the solenoid valve which controls the supplyof water to the solution for preventing the supply of water to thesolution when the pump is not operating.

15. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the systemaud'baving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of thecirculating-solution, a water reservoir,'means lncluding a'water supplypipe and a float valve for supplying water to a predetermined level inthe water reservoir, a

water delivery pipe for supplying water from the reservoir into thesolution in the system, a solenoid valve in the water supply pipe, asolenoid valve in the water delivery pipe, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valves and responsive to the electrical conductivityof the solution and controlling said solenoid valves to supply waterfrom the water reservoir to the solution and to shut off the supply ofwater to the water reservoir when the electrical conductivity of thesolution falls below a desiredvalue, and to shut off the supply of waterfrom the water reservoir to the solution and to supply water to thewater reservoir when the electrical conductivity of the solution risesabove the desired value, for maintaining the water content of thesolution at substantially the desired value and for preventing an excesssupply of water to the solution, and switch means operatively connectedto the pump and electrically connected to the solenoid valve whichcontrols the supply of water to the solution for preventing the supplyof water to the solution when the pump is not operating.

16. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the system andhaving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of the circulatingsolution, means including a pipe and a solenoid valve for supplyingwater to the solution in the system, and an electrical resistanceresponsive controller electrically connected to said metallic electrodesand said solenoid valve for controlling the supply of water to thesolution in accordance with the electrical conductivity of the solutionfor maintaining the water content of the solution at substantially adesired value, and a signal light electrically connected to saidcontroller and illuminated while water is being supplied to thesolution, and switch means operatively connected to the pump andelectrically connected to the solenoid valve which controls the supplyof water to the solution for preventing the supply of water to thesolution when the pump is not operating.

17. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dis persed as to form asubstantially clear homogeneous solution, the improvement whichcomprises electrical conductivity means connected into the system andhaving a pair of spaced metallic electrodes, the space between saidmetallic electrodes being traversed by a portion of the circulatingsolution, a water reservoir, means including a water supply pipe and afloat valve for supplying water to a predetermined level in the waterreservoir, a water delivery pipe for supplying water from the reservoirinto the solution in the system, a solenoid valve in the water supplypipe, a solenoid valve in the water delivery pipe, and an electricalresistance responsive controller electrically connected to said metallicelectrodes and said solenoid valves and responsive to the electricalconductivity of the solution and controlling said solenoid valves tosupply water from the water reservoir to the solution and to shutageraieee off the supply ofiwaterto the water reservoir when theelectrical conductivity of the solution falls below a water reservoir tothe solutionand-to supply water to the to the solution, and switch-meansoperatively connected to the pump and electrically connected to thesolenoid valve which controls the supply of water to the solution forpreventing the supply-- of water to" the solution whenthe pump is notoperating. 1

18. In a dry cleaning system which includes a washer adapted to liold'fabricsto be dry cleaned, a filter, conduits interconnecting the washerand filter and apump' for circulating through-the washer, filter andconduits a water-immiscible organic dry cleaning solvent which" isactivated by small proportions of an oil-soluble nonvolatile drycleaningdetergent and water so finely dispersedas to-forma substantially clearhomogeneous solution, the improvement which comprises a substantiallycylindrical housing connected into one of the" conduits for circulationof the solution therethrough, a pair of spaced apart concentricallyarranged tubular metallic electrodes concentrically mounted inthe'housing and electrically insulated from each other and the housing,the

space between said concentrically arranged tubular metallic electrodesbeing-traversed by a portion of the circulating solution, theinsidediameter of the conduits and themounting for" the tubular metallicelectrodes heing suchvas to" provide substantially uninterrupted flowo'f'the'" solution through the system, and an electricalresistanceresponsive device electrically connected to said metallic'electrodes for responding to the electrical conductivity of thesolution;

19. In a; dry cleaning system which includes a washer adapted. to holdfabrics to be dry cleaned, a filter, con duits interconnectingthewasher' and filter and apump-for circulating through the washer,filter and? conduits a water-immiscible organic. dry" cleaning? solventwhich is activated. by small proportionsof an oil soluble non=- volatiledry cleaning" detergent and Water so finely dis persed' asitoi form asubstantially clear homo'geneous so'lu tion, the conduit circulating thesolution from the filter to the washer: having' a verticallportionadjacent the filter, the improvement which.- comprises a substantiallycylindrical housing connected ihto said" vertical portion of saidconduit for circulation ofthe solution therethrou'gh, a pair of spacedapart concentricallyarranged tubular metallic electrodes concentricallymounted. in the housing and electrically insulatedfi'o'm' each other andthe housing, the space between. said. concentrically-arranged tubularmetallic electrodes being traversed by a portion of the circulatingsolution and an electrical resistance responsive device electricallyconnected to said metallic electrodes for responding to the electricalconductivity of the solution.

20. An electrical conductivity device, adapted to be connected into aconduit for determining the electrical conductivity of a fluid flowingthrough the conduit, comprising a substantially cylindrical housing,fittings at the ends of the housing for connecting the housing into theconduit, a pair of spaced apart concentrically arranged tubular metallicelectrodes, a pair of annular spacer members receiving the ends of thetubular metallic electrodes for concentrically supporting the same,means for removably securing the spacer members in the substantiallycylindrical housing for concentrically mounting the tubular metallicelectrodes in the housing, said annular spacer members allowing freeflow of fluid through the inner tubular metallic electrode and havingopenings for allowing free flow of fluid between the inner and outer [ta7 tubular" metallic electrodes; said annular spacer memb'ers beingformed of electrical insulatinggmaterial for electrically insulating thetubular metallic electrodes from each other and from the housing, andmeans providing.

external' 'electrical connections to the tubular metallic electrodes.

21. An electrical conductivity device, adapted to be connected into abend in a conduit for determining the electrical conductivity of a fluidflowing through the conduit, comprising a substantially cylindricalhousing, a fitting connected at one end of the housing for connecting'the housing concentrically with one portion of the conduit; a T-fittinghaving one of its through legs connectedtoth'e other end of the conduit,its normal leg connecte'd to the other portion of the housing and itsother through'leg closed bya removable plug, a pair'of spaced apartconcentrically arranged tubular metallic electrodes, a pair of annularspacer members receiving the ends of the" tubular metallic electrodesfor concentrically supporting the same, means for removably securing thespacer-members in the substantially cylindrical housing forconcentrically mounting the tubular metallic electrodes: in the housing,said tubular metallic electrodes and spacer members being removablefromthe housing through" the T-fitting when the securing means for thespacer'members and the plug are removed, said annular spacer membersallowing free flow of fluid through the inner tubular metallic electrodeand having openings for allowingfree flow of fluid between the inner andouter tubular" metallic electrodes, said annular spacer memhers heing'formed of electrical insulating material for electrically insulating thetubular metallic electrodes from each other and from the housing, andmeans providing external electrical connections to the tubular metallicelectrodes.

22-. An electrical conductivity device, adapted to be connected into.aconduit for determining the electrical conductivity of a fluid flowingthrough the conduit, comprising asubstantially cylindrical housinghaving an inside diameter larger than the inside diameter of theconduinfittings at the ends of the housing for connectingthe' housinginto the conduit, apair of spaced apart concentrically arranged tubularmetallic electrodes, a painof annular spacer members receiving the endsof the: tubular metallic electrodes for concentrically supporting thesame,- means for removably securing the spacer members in thesubstantially cylindrical housing for concentrically mounting thetubular metallic electrodes in the housing, the diameters of saidtubular metallic 'electr'o'desgthe inside diameters of said housing andthe; construction of. said spacer members being such as torallow'freeand'substantially unobstruct'edflow of fluid throughlthe-inner tubularmetallic electrode, between the inner andouter tubular metallicelectrodes and through theicondirit' said annular spacer members beingformed of electrical insulating material for electrically insulating thetubular metallic electrodes from each other and from the housing, andmeans providing external electrical connections to the tubular metallicelectrodes.

23. An electrical conductivity device, adapted to be connected into aconduit for determining the electrical conductivity of a fluid flowingthrough the conduit, comprising a substantially cylindrical housing,fittings at the ends of the housing for connecting the housing into theconduit, a pair of spaced apart concentrically arranged tubular metallicelectrodes, a pair of spacer members each having a central opening, aseat adjacent the opening for receiving the inner tubular metallicelectrode and a seat of larger diameter for receiving the outer tubularmetallic electrode, for concentrically supporting the electrodes, meansfor removably securing the spacer members in the substantiallycylindrical housing for concentrically mounting the tubular metallicelectrodes in the housing, the central openings in the spacer membersallowing free flow of fluid through the inner metallic electrode, saidspacer members having openings therethrough between the seats thereoffor allowing free flow of fluid between the inner and outer tubularmetallic electrodes, said annular spacer members being formed ofelectrical insulating material for electrically insulating the tubularmetallic electrodes from each other and from the housing, and meansproviding external electrical connections to the tubular metallicelectrodes.

24. An electrical conductivity device, adapted to be connected into aconduit for determining the electrical conductivity of a fluid flowingthrough the conduit, comprising a substantially cylindrical housing,fittings at the ends of the housing for connecting the housing into theconduit, a pair of spaced apart concentrically arranged tubular metallicelectrodes, a pair of spacer members each having a central opening, aseat adjacent the opening for receiving the inner tubular metallicelectrode and a seat of larger diameter for receiving the outer tubularmetallic electrode, for concentrically supporting the electrodes, meansfor removably securing the spacer members in the substantiallycylindrical housing for concentrically mount-, ing the tubular metallicelectrodes in the housing, the central openings in the spacer membersallowing free flow of fluid through the inner metallic electrode, saidspacer members having openings therethrough between the seats thereoffor allowing free flow of fluid between the inner and outer tubularmetallic electrodes, said spacer members having openings therethroughoutwardly from the seat of larger diameter for allowing free flow offluid between the outer tubular metallic electrode and the housing, saidannular spacer members being formed' duits interconnecting the washerand filter and a pump,

for circulating through the washer, filter and conduits awater-immiscible organic dry cleaning solvent which is activated bysmall proportions of an oil-soluble nonvolatile dry cleaning detergentand water so finely dispersed as to form a substantially clearhomogeneous solution, the improvement which comprises an electricalconductivity device including a substantially cylindrical housing,fittings at the ends of the housing for connecting the housing into oneof the conduits for circulation of the solution therethrough, a pair ofspaced apart concentrically arranged tubular metallic electrodes, a pairof annular spacer members receiving the ends of the tubular metal-- licelectrodes for concentrically supporting the same,

means for removably securing the spacer members in the substantiallycylindrical housing for concentrically mounting the tubular metallicelectrodes in the housing, said annular spacer members allowing freeflow of the solution through the inner tubular metallic electrode andhaving openings for allowing free flow of the solution between the innerand outer tubular metallic electrodes, said annular spacer members beingformed of electrical insulating material for electrically insulating thetubular metallic electrodes from each other and from the housing, andmeans providing external electrical connections to the tubular metallicelectrodes, and an electrical resistance responsive device electricallyconnected to said external electrical connections for responding to theelectrical conductivity of the solution.

26. In a dry cleaning system which includes a washer adapted to holdfabrics to be dry cleaned, a filter, conduits interconnecting the washerand filter and a pump for circulating through the washer, filter andconduits a water-immiscible organic dry cleaning solvent which isactivated by small proportions of an oil-soluble nonvolatile drycleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the improvement whichcomprises an electrical conductivity device including a substantiallycylindrical housing, fittings at the ends of the housing for connectingthe housing into one of the conduits for circulation of the solutiontherethrough, a pair of spaced apart concentrically arranged tubularmetallic electrodes, a pair of annu- 'lar spacer members receiving the.ends of the tubular metallic electrodes for concentrically supportingthe same, means for removably securing the spacer members in thesubstantially cylindrical housing for concentrically mounting thetubular metallic electrodes in the housing, said annular spacer membersallowing free flow of the solution through the inner tubular metallicelectrode and having openings for allowing free flow of the solutionbetween the inner and outer tubular metallic electrodes,

vsaid annular spacer members being formed of electrical insulatingmaterial for electrically insulating the tubular metallic electrodesfrom each other and from the housing, and means providing externalelectrical connections to the tubular metallic electrodes, meansincluding a pipe and a solenoid valve for supplying water to thesolution in the system, and an electrical resistance responsivecontroller electrically connected to said external electricalconnections and said solenoid valve for controlling the supply of waterto the solution in accordance with the electrical conductivity of thesolution for maintaining the water content of the solution atsubstantially a desired value.

References Cited in the file of this patent 530,617 Canada Sept. 18,1956

